The banks have been here before in various forms. I know Barclays had a go with Sage and then Quickbooks at different times as a way of bringing small businesses onboard and into a better way of running their businesses.
I seem to recall that staff changes in the bank at the client level made the whole thing something less than its potential. The product needed pushing by the account manager. If they do not hang around long enough, the outcome was disappointing.
How will returns for travel agents (TOMS margin scheme) and for car dealers (another margin scheme) be filed. These are not tiny corners of the economy.
TOMS is enough to give you nervous breakdown without any attempt to force it through MTD. I guess the return amendment schedule will remain in place effectively breaking any chance at end to end digital.
I cannot imagine any software developer being bothered to account for the annual margin % applied to sales and recalculating it it at the end of the accounting year, whenever that may be.